Hinge last



Jung; 30, 1931. c, sTURGlS I 7 1,811,901

HINGE LAST Filed Oct. 10. 1928 Patented June 30, 1931 UNlTED STATES Parser entice CAR-L L. STD RG13, OE BROCKTGIT, MASSACHOSETTS, ASSIGNOR, BY EVIESNE ASSIGN- lrIENTS, TO UNITED SHOE MACHINERY CORPORATION, OF PATERSON, NEW JERSEY,

A CORPORATION OF NEN JERSEY HINGE LAs'r f Application filed October 10, 1928. Serial No. 311,686.

This invention relates to hinge lasts of the impositive lock type. In this type of last the last parts are movable from extended position by pressure alone, and the hinge mechanism is so constructed as to ofier an increasing resistance to collapse over a substantial movement from extended position. This increasing resistance has generally been effected by means of the compression of a locking spring, which, prior to the present invention, has been mounted in a hole in the instep portion of the last forepart and compressed by a hinge member mounted in the last heel part, pivoted in the forepart, and arranged to compress the spring by virtue of its pivotal movement in the forepart.

A difficulty inherent in hinge lasts is the danger of splitting the wood in the joint surface between the last parts when the last is in the leveling machine, for example. It is necessary, in hinged lasts, to provide some means to prevent relative twisting or lack of alinement between the last parts. This has been very successfully accomplished by forming a circular knuckle on one last part extending into a corresponding concavity in the other, the center of relative swing of the last parts in collapse being at the center of the knuckle. Obviously it is necessary that a bonding link extend from a pivot pin in the knuckle into the last part containing the concavity, to hold the last parts together.

The knuckle has been placed on the forepart in some lasts, for example, that shown -in United States Letters Patent to C errish,

No. 1,007,092, Oct. 31, 1911, and Holbrook No. 907,693, Dec. 22, 1908; and on the heel part in others, for example, that shown in United States Letters Patent to l rentler, No. 1,094,153, April 21, 1914., Each of these types has inherent disadvantages. in order to obtain adequate horizontal bearing between the last parts in the Gerrish type the lower part of the knuckle cut extends considerably forward into the shank part of the last, whereas it should not be located much in advance of the heel plate. In lasts of the H0lbrook type the cut is extended backward from the bottom of the knuckle, forming a shelf under the knuckle. This gives rise to a great deal of 'diihculty in that the vertical pressure of the heel part against this sharply angled shelf when the last is in a leveling machine, for example, often starts a split at the corner between the front end of the and the bottom of the knuckle.

In lasts of the Krentl-er type, these diffi culties are both avoided, since the knuckle is on the heel part, and itsbottom end can be placed as far to the rear "as desired, While there isno sharp corner so situated that the shelf leveling machine pressure can start a split there; A disadvantage,however, does arise, in that the bonding link which connects the forepart to the heel part knuckle is substantially motionless in the forepart,and an extra bonding member mounted in the heel part is necessary to move in the forepart'during collapse and co-operate with the impositive'lock ing spring in the forepart, thus involving additional expense.

v The present invention avoids all these chi"- culties by placing the locking spring in the lower part of the heel part, where there is bodiment of the invention shown in the drawings, in which r Fig l shows a last embodying the invention in extended position; and

Fig. 2 shows the last in collapsed position. 7

The illustrated last'comprises a heel part 10 and a forepart 12 and is divided :by a cylindrical cut forming a knuckle 14; on the heel part 10, and a corresponding concavity on the forepart 12, and then emerging vertically from the last bottom. A pin 16 is inserted at the center of the knuckle and is coaxial with it. A link 18 is pinned into a hole suitably formed in the forepart by a transverse pin 20, and is pivoted on the pin 16, thus holding the last parts together and permitting relative rotation of them about the pin 16. The link 18 has a rearwardly extending projection 22 arranged to press against a ball 24: seated in the end of a spiral locking spring 26 mounted in a hole 28 in the lower portion of the heel part. The partsare so arranged that as the heel part swings in the collapsing movement the projection 22 will move over the ball 2 1 and push it back to compress the spring 26, coming to a dead center on the ball 24 midway of the collapsing movement, the last offering increasing resistance to movement from either extended or collapsed position.

As already suggested, the hole 28 does not unduly weaken the thick heel part bottom, even in a small last, and the long curved shelf 80 of the knuckle receiving surface of the forepart offers ample horizontal support against twisting stresses and provides no sharp corner at which a split can be started by vertical pressure upon the shelf.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is 1. A hinge last comprising a forepart, a heel part having a cylindrical knuckle on its front surface spaced from its tread surface, the forepart having a cylindrical concavity in its rear surface fitting said knuckle, bonding means between the last parts consisting of a single link mounted in the forepart and pivoted at the axis of the knuckle, and a spring mounted in the heel part and arranged to be compressed by the rear end of the link as the last parts are relatively moved from extended position.

2. An impositive-lock hinge last comprising a forepart, a heel part having a cylindrical knuckle on its front surface, the lower surface of said knuckle being substantially spaced from the tread surface of the heel part, the forepart having a cylindrical concavity in its rear surface fitting said knuckle, bonding means between the last parts consisting of a single link mounted in the fo-repart and pivoted at the axis of the knuckle, a rearwardly extending projection on the link, and a spring mounted in a hole formed in the heel part and having a ball seated in its front end and arranged to co-operate with the projection to compress the spring when the last is moved from extended or collapsed position.

In testimony whereof I have signed my name to this specification.

CARL L. STURGIS. 

